[T] Example usage of regex project file parameter.

Tests/Data/Mechanics/Burgers/cube_1e0.prj

@@ -238,13 +238,7 @@
     </linear_solvers>
     <test_definition>
         <vtkdiff>
-            <file>cube_1e0_pcs_0_ts_1_t_0.000100.vtu</file>
-            <field>displacement</field>
-            <absolute_tolerance>1e-16</absolute_tolerance>
-            <relative_tolerance>1e-16</relative_tolerance>
-        </vtkdiff>
-        <vtkdiff>
-            <file>cube_1e0_pcs_0_ts_101_t_1.000000.vtu</file>
+            <regex>cube_1e0_pcs_0_ts_.*_t_.*.vtu</regex>
             <field>displacement</field>
             <absolute_tolerance>1e-16</absolute_tolerance>
             <relative_tolerance>1e-16</relative_tolerance>